Anyone know the proper voltage drop when the GPR engages?

I'm getting a 7 volt draw right now, which is practically shutting the truck down, so no start. And I don't have a bypass wired in. Nor do I remember which wire is what anymore cause I put the damn stancore in like 13 years ago now.

I got a spare GPR thankfully, but again, don't remember which wire is what and goes where.

I really need to do the push button install.

Can't tell if I got a random UVCH problem, or GPR is just bad. I'm going to guess GPR, because its the most likely to fail age wise. Glow plugs are recent, and I did the SD uvch upgrade. So pin burnout chance is still there but really low.

I got the voltage drop running a meter on the battery and hard shorting the GPR and started seeing 5volts on the meter. Batteries are new this year too and connections are good.

 

You should get about 1 volt drop when the glow plugs are active.
If you are 7 volts or 7 volt drop (your wording was vague) you have battery issues.
About 11.5 volts give or take a .01-.03 volts is what you should see when glow plugs are active.

If your batteries are not resting at 12.6 volts after sitting several hours that is a good indication they are likely done.
Charge them up with a proper charger and test them at the truck stop. The local corner store hand held tester will not do the job properly.
This is the place to start.

 

I doubt they are done after 8 months, but possible.
I've been dealing with some alternator issues though as well. The remans are just not as good as the old bosh's, and you cannot get those anymore. And mine finally failed earlier this year and the replacement has been giving me weird readings.
And being as the truck has been technically sitting for a few weeks. I drove it 2 miles a few days ago from a 20 degree cold start with no issues.

Having dealt with a lot of battery issues over the years, I'm not seeing it as a battery problem. Especially from starting this truck for a long time with bad batteries and never seeing a voltage draw that hard from the Glow plug system. Which leads me to something being shorted from what I'm seeing from my meters. The batteries would have to be so outright trashed for it to draw that much to shut the truck down with a jump going at the same time.

 

https://www.ford-trucks.com/forums/1...ou-cranky.html
I do the cleaning in above link and battery trouble shooting when ever I have an issue with volt drop

 

Yeah, with my old cables, I gotta do it twice a year, its annoying.

No useful advice from anyone, so guess I'm pulling VC's and checking for shorts. Oh well.

 

I was thinking about this while folding laundry. (Being on vacation makes me domesticated). I don’t think it is the GPR. It just shunts power as it is demanded. Either there is a short somewhere or the batteries are not providing enough power. The batteries may not be up to the task due to the charging issue you mentioned. I would use the IDM connector to perform the continuity test before pulling the valve covers. It is easy to do and it may point to a solution before pulling the covers.

you are as good as any of are at troubleshooting one of these things. Just walk it through until you find the culprit. I just don’t think the GPR is it.

 

Agreed. To pull that much current is usually welding something, or at least letting smoke out.

 

Yeah, I"m not really sure why I thought GPR. but honestly. I rarely have to work on this thing. All the info I had 8-10 years ago is long gone. Everythign else is basic troubleshooting stuff.

it was more of a "if anyone can think of anything else" and everyone is screaming "bad batteries."

Which I wont say it isn't the issue, but its really odd for 8 month old batteries to be bad though unless there is some other circumstance causing that.

And the voltage drop I'm seeing, I'm not letting that ride for more than a brief second. I saw 5 volts on the meter and was like "nope."
And whatever draw there is is so high its shutting the GPR relay right off like there is a short.

I'll figure it out.

It was more of a "not now" sort of thing. Cause this isn't the best time of year to find parts either.

 

I hear ya. I had to work on one last week. While doing that, the other two started misbehaving. It’s like they coordinate it.

 

Well this is even more annoying.

Everyone says batteries are bad. Okay sure whatever.

I put them on charger, charger getting WAY to hot. like. okay wow. Not normal. Both batteries. okay possibly bad. I see a .2 volt drop overnight with batteries sitting in climate control. That definitely not good.

Take them to interstate this morning "oh these are good, they just need charge." I explain to him what I was seeing and going on.

Like bro... They are not even a year old from the MFG, made in feb of this year. And you're going to now try and tell me they need reconditioning?

Ughhhh. And with no batteries, I cannot even check the loads on the rest of the system, and of course he wont load test them without them being fully charged.

So this is just getting annoying at this point.
Cause now i'm going to get back fully charged batteries that will work for a bit then die again and waste my time if they were bad.


But the other problem I'm having here too is, I'm trying to figure out why the GP system is pulling 7 volts when I meter the battery. Cause I've had trashed batteries before and they would only drop 1 or 2 volts.

 

What sort of weird readings?

 

it's hard telling, but sometimes I'll see 12 volts on the gauge vs 14. But because the sensor plug on our alternators is so finicky, I dont' put a huge stake in it unless the idiot gauge on the dash is showing really crazy stuff.